Artificial photo-synthesis technologies that use a photocatalyst to produce useful fuel from carbon dioxide and/or conversion of carbon dioxide to the same are now a global issue. Such a method of preparing a useful fuel using carbon dioxide and/or converting carbon dioxide to the same substantially utilizes only water and solar light, therefore, may be the most eco-friendly and sustainable technique. The fuel produced by the foregoing method may include hydrocarbons having 1 to 4 carbon atoms, preferably, aliphatic hydrocarbons having 1 to 4 carbon atoms, and more preferably, methane.
Methane has the simplest form among hydrocarbons, however, is a main component of natural gas generating the largest energy (55.7 kJ/g) per unit mass and hence is generally known as a useful fuel.
In order to convert carbon dioxide (CO2) to methane using solar energy, it is important to use an excellent photocatalyst.
Recently, gallium (III) oxide (Ga2O3) has attracted worldwide attention since it has superior photo-catalytic properties and high reduction potential to render CO2 to be converted to methane. However, studies on conversion of CO2 to methane using gallium (III) oxide have not yet been reported.
Accordingly, the present invention relates to a method of manufacturing a porous gallium (III) oxide photocatalyst with novel structure and form, and a method for production of hydrocarbons, preferably, aliphatic hydrocarbons having 1 to 4 carbon atoms, and more preferably, methane from CO2 or for conversion of CO2 to any of the foregoing hydrocarbons or methane by using the aforesaid porous gallium (III) oxide photocatalyst.
In this regard, prior arts to which the present invention pertains may include the following:
Grimes et al. have disclosed photo-synthesis wherein titanium dioxide nanotubes (TiO2 nanotubes) synthesized through anodization is used to generate methane from CO2 and water [High-Rate Solar Photocatalytic Conversion of CO2 and Water Vapor to Hydrocarbon fuels, Nano Lett., 2009, 9, 731]. However, it is known that such TiO2 material is less effective in reducing CO2 to produce methane due to a relatively low chemical reduction potential thereof [Toward Solar Fuels: Photocatalytic Conversion of Carbon Dioxide to Hydrocarbons, ACS nano, 2010, 4, 1259].
Further, Tanaka et al. have conducted reduction of CO2 from hydrogen as well as CO2 using a β-Ga2O3 photocatalyst, which is known to have high reduction potential [Effect of H2 gas as a reductant on photoreduction of CO2 over a Ga2O3 Photocatalyst, Chem. Phys. Lett., 2008, 467, 191]. However, it was found that the above photocatalyst did not produce methane, but instead generated carbon monoxide (CO), which is substantially an intermediate stage of the reduction.